1. Field of the Invention
This invention relates in general to the construction of breathing apparatus and in particular to a new and useful humidity exchanger in an apparatus for respiration and anasthesia wherein the humidity contained in the exhaling air is separated therefrom and the separated water is evaporated into the inhaling air.
2. Description of the Prior Art
In apparatus for respiration and anasthesia it must be made certain that the respiratory tracts of the patient do not dry out. The risk of the patient's tracts drying out exists particularly when the inhaling air is fed to the patient through an intratracheal catheter or through a tracheotomy canule. This is because the rinopharyngal area which normally moistens the inhaling air is then bypassed.
A known apparatus for such use comprises a heat container arranged in the heat cover and connected to the nose or mouth through a tube which is filled with metal particles such as filings or wire pieces. The tube is divided into two compartments to insure the flow of the exhaling air and the inhaling air on different paths. Valves control the air through the compartments. An asbestos lining can be saturated with water to moisten the inhaling air. The exhaling air always flows through one compartment while the inhaling air always flows through the other compartment. The exhaling air heats the heated container which is also heated by the body temperature of the head. In the heat exchanger the inhaling air takes over the heat from the heat container. In the heat container it is only slightly cooled by colder inhaling air if it is cooled at all and this is due to the additional heating by the body temperature so that there is little condensation of water from the exhaling air. In addition this condensed moisture remains in the compartment that is traversed only by the exhaling air. The bulk of the water is eliminated with the exhaling air. Moistening of the inhaling air is thus not achieved. Such moistening can only be effected by the water from the asbestos lining. Moistening therefore depends on the care of the attendant. This machine is not known for use in connection with apparatus for artificial respiration and anasthesia.
Another known humidity exchanger in which the humidity contained in the exhaling air is separated and the separated water of condensation is evaporated into the inhaing air includes a steam condenser which is filled with metal wires, screens or cloths, etc. It can also be filled with a porous material of good thermal conductivity. The connection between the parts of the steam condenser and the exhaling air and the inhaling line are so designed that the water can pass through. Hence only the condensed water is picked up in the inhaling air current. But since condensation takes place only until the temperature is equalized between the exhaling air and the inhaling air current, only the portion obtained from the exhaling air current can be utilized for moistening the inhaling air. A disadvantage is that the water contained in the exhaling air which still has a relative humidity of 100% after temperature equalization with the inhaling air discharged.